Chromatography is a well-known analytical chemistry technique for identifying individual components in mixtures of component where ordinary methods of separation and identification are not feasible. Although the technique has been applied to mixtures of gases as well as to mixtures of liquids, the present invention relates solely to the latter, known as "liquid-phase" chromatography.
Various means of detecting different components in the liquid mixture are known based on the fact that different chemical compounds have different physical and chemical properties and characteristics. For example, the absorption of ultraviolet light or visible light, refractive index, heat of absorption, ionization, electrical conductivity, and fluoresence are properties upon which chromatographic analyses have been used. In each instance a cell is needed through which flows a small volume of liquid to be analyzed, and the cell must be equipped to provide means for detecting a property. In the present invention a flow cell is provided which is capable of detecting photoionization, photoacoustics, or fluorescence.